The present invention relates to electronic temperature measurement circuits. More particularly, the present invention relates to a monolithic integrated CMOS circuit for sensing temperature and for providing a binary coded decimal output signal.
Prior techniques for temperature measurement and conversion thereof to digital data required a considerable number of separate parts and interconnected components with concomitant power consumption.
For monitoring applications which require long term accuracy and stability, the specification and use of high precision components with careful part testing, screening and selection of the components was required. The drawbacks of those techniques included the bulk of the resultant circuitry, the time and expense required for manufacture, power supply requirements and dissipation which usually required connection to a primary power source and did not readily provide for self-contained battery operation at low current drain.
While it has been proposed to utilize bipolar bandgap voltage reference circuits in thermometer applications (application note AN-18 entitled "Thermometer Applications of the REF-02," published by Precision Monolithics Inc. in 1976), the use of such techniques in low power consumption CMOS circuitry has not heretofore been thought to be practical.